1. Field of the Invention
The present invention is in the field of construction equipment and pertains particularly to methods and apparatus for conveying materials onto and from a rooftop.
2. Discussion of the State of the Art
In the field of construction equipment, more particularly in the roofing industry, roofing materials have traditionally been carried or lifted onto a rooftop manually by the workers without any mechanical assistance. More recently, conveyor type systems including those that are hydraulically powered have been developed and used to convey heavy roofing materials such as roofing shingles for example from a ground location to the rooftop location where those materials will be applied in construction.
One such system is known to the inventor and is included herein at least by reference to U.S. Pat. No. 5,984,077 granted for a mobile overhead conveyor system. This system as known to the inventor may be referred to herein as Frye et al. The system of Frye et al is installed on a delivery truck that may deliver materials to a rooftop construction site. The system consists of a hydraulic rotary turret type base that supports, via a hydraulic lift mechanism or mechanisms, a boom structure housing a conveyor that can be operated under hydraulic power and positioned at an azimuth sufficient to convey roofing materials from the truck directly to a rooftop or from the rooftop back to the truck.
This system includes a feature that aids in the safety of operators and workers where electrical hazards exist such as nearby power lines or close electrical storm in that the main structural components of the boom, more particularly the side rails of the boom structure are fabricated from a non-conductive material such as fiberglass reinforced plastic beams. Also in this system, the conveyor belt is fabricated of a resilient and nonconductive polypropylene material. However other components include metals and pose a hazard still in some electrical circumstances.
It is critical that regular maintenance is conducted on a boom-assisted conveyor such as the one referenced above due in part to complexity of operation of the hydraulic components and controls for raising lowering and positioning the boom for materials delivery and return from a rooftop. Forces acting against such a conveyor include a large weight factor associated with moving heavy roofing materials up the conveyor and onto the roof. An operator on the roof may control the conveyor belt drive mechanism via a motor control unit made available at the upper (roof) end of the boom structure.
Such heavy material loads on the conveyor cause friction wear to components disposed at the upper end of the boom structure when the material is offloaded while the conveyor is running. This causes the wearing off of any protective non-conductive coatings applied to certain metallic components or other materials enclosing metal reinforcement materials of the system of Frye et al, such as metal in the conveyor “lugs” installed on the belt, for example.
Certain drive components (chain, sprocket), and other structural belt support components may undergo a buildup of static electricity. The system of Frye et al builds up static electric charge resulting from continued operation in ferrying materials on to and off of the rooftop. The above system is liable to produce a significant static shock under the right atmospheric conditions during operation of the conveyor to move materials, such shocks may be experienced by operators touching or coming too close to a worn portion of the boom structure or to any of the above mentioned components.
Another component that may become worn through operation is the conveyor belt by frictional contact with components of the system such as those touching the belt during motion. The wear of the belt may occur at the edges of the belt and to the interior surface of the belt from friction caused by material contact and by component contact. Therefore, what is clearly needed is a conveyor system adaptable to a truck-mounted hydraulic turret and boom structure that eliminates or greatly reduces the problems described above.